Added changes to support mTLS authentication

[gyaneshgouraw-okta]

Changes

Please describe both what is changing and why this is important. Include:

• Added relevant changes to start supporting mTLS authentication
• As part of the change a new boolean parameter useMTLS, if passed as true, it will append mtls prefix to required authentication endpoints.
• If value useMTLS is true , validation for clientSecret & client assertion signing key will be skipped.

References

Please include relevant links supporting this change such as a:

• mTLS auth0 documentation - Link

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• Verified different client authentication flows like passwordless, database & other oauth methods
• mTLS configuration worked correctly, required access token were received on successful request
• [x] This change adds unit test coverage
• [ ] This change adds integration test coverage

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All existing and new tests complete without errors